Correct contract bridge / by E.V. Shepard ; including the official Laws of contract bridge adopted by the Whist Club, New York, and by all the leading clubs in America.

170 CORRECT CONTRACT BRIDGE
"courtesy raise," without at least a single definite
trick.
The slam signal also may be given as follows: by
a forced bid one trick higher than required; by
jumping partner's opening bid of one to three; by
bidding a suit already named by an opponent, provided your partner has already made a suit declaration.
In general a slam signal by the original declarer
of a suit indicates the ace and a trump suit sufficiently solid to avoid the loss of more than a single
trump trick (Five trumps including four honors or
six trumps headed by A K Q or A Q J). Opening
bids of two require in major suits probable ability
to win a minimum of seven tricks; similar bids in
minor suits indicate probable ability to win at least
eight tricks. Greater total strength than stated
above, or a hand containing at least five sure tricks
divided among not less than three suits and better
adapted to a trump than a no-trump make, may
justify an opening bid of a 5-card suit that is less
solid than required above.
A slam signal by the assisting hand requires a
minimum of six assisting tricks and better than
average trump support.
An opening bid of 2-No Trumps is merely a game
signal; it rarely anticipates a slam.
The great majority of slam signals result in contracting running no higher than game, but many
hands without slam hopes (Due to lack of aces or to
the openness of the trump suit) urge employment
of slam signals, followed by the "reverse signal."